Time synchronized radar transmissions

ABSTRACT

Certain aspects of the present disclosure provide techniques for radar detection by an apparatus. In certain aspects a method for radar detection by an apparatus includes selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles. The method further includes performing radar detection using the selected radar transmission parameters and the reference time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of and priority to: U.S. Provisional Patent Application Ser. No. 62/700,460 filed Jul. 19, 2018, which is incorporated by reference herein in its entirety as if fully set forth below and for all applicable purposes.

BACKGROUND Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for performing time synchronized radar transmissions.

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few.

In some examples, a wireless multiple-access communication system may include a number of base stations (BSs), which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs). In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation, a new radio (NR), or 5G network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., which may be referred to as a base station, 5G NB, next generation NodeB (gNB or gNodeB), TRP, etc.). A base station or distributed unit may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit).

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. New Radio (NR) (e.g., 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. It is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL). To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

Vehicle to everything (V2X) communications seek to enable vehicles to communicate with one another to provide a host of services, including vehicle to vehicle communications (V2V), vehicle to infrastructure (V2I) communications, vehicle to grid (V2G) communications and vehicle to people (V2P) communications.

Radar detection systems complement V2X communications. Radar based detection systems use electromagnetic waveforms for several reasons including enhanced navigation and obstacle avoidance. In the evolution towards driverless vehicles, radar based detection systems play an ever increasing role. However, as more vehicles deploy radar based detection systems, interference become a larger problem. Accordingly, improvements to radar based detection systems are needed.

BRIEF SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between access points and stations in a wireless network.

Certain aspects provide a method for radar detection by an apparatus. The method includes selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles. The method further includes performing radar detection using the selected radar transmission parameters and the reference time.

Certain aspects provide a means for radar detection by an apparatus. The apparatus includes a means for selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles. The apparatus further includes a means for performing radar detection using the selected radar transmission parameters and the reference time.

Certain aspects provide a non-transitory computer readable storage medium that stores instructions that when executed by a processor of an apparatus cause the apparatus to perform a method of radar detection. The method includes selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles. The method further including performing radar detection using the selected radar transmission parameters and the reference time.

Certain aspects provide a radar detection apparatus including a memory and a processor. The processor is configured to cause the radar detection apparatus to select one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles. The processor is further configured to cause the radar detection apparatus to perform radar detection using the selected radar transmission parameters and the reference time.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram conceptually illustrating a design of an example base station (BS) and user equipment (UE), in accordance with certain aspects of the present disclosure.

FIGS. 3A and 3B illustrate certain V2X communications, in accordance with certain aspects of the present disclosure.

FIGS. 4A and 4B illustrate transmitted FM-CM radar waveforms, in accordance with certain aspects of the present disclosure.

FIG. 5 illustrates received FM-CM radar waveforms, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates data extrapolation from a transmitted and received FM-CM radar waveform.

FIG. 7 illustrates radar detection, in accordance with certain aspects of the present disclosure.

FIG. 8 illustrates radar waveforms, in accordance with certain aspects of the present disclosure.

FIG. 9 illustrates a block diagram of a method of radar detection, in accordance with certain aspects of the present disclosure.

FIG. 10 illustrates reference time synchronized radar waveforms, in accordance with certain aspects of the present disclosure.

FIG. 11 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for time synchronized radar transmissions.

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

The techniques described herein may be used for various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS).

New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

New radio (NR) access (e.g., 5G technology) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a New Radio (NR) or 5G network. NR wireless communication systems may be used to communicate radar detection system information (e.g., reference time information (e.g., UTC), a clock signal, codebooks (e.g., radar transmission parameter codebooks), sensor information (e.g., radar transmission parameters), etc.) to facilitate time synchronized radar transmissions. User equipment (UE) 120 a includes a radar system module for performing radar detection and radar transmission between other similarly equipped UEs. Base station (BS) 110 a may perform and/or direct the execution of processes for the techniques described herein.

As illustrated in FIG. 1, the wireless network 100 may include a number of BSs 110 and other network entities. A BS may be a station that communicates with UE. Each BS 110 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and next generation NodeB (gNB), new radio base station (NR BS), 5G NB, access point (AP), or transmission reception point (TRP) may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

A base station (BS) may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, the BSs 110 a, 110 b and 110 c may be macro BSs for the macro cells 102 a, 102 b and 102 c, respectively. The BS 110 x may be a pico BS for a pico cell 102 x. The BSs 110 y and 110 z may be femto BSs for the femto cells 102 y and 102 z, respectively. A BS may support one or multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, a relay station 110 r may communicate with the BS 110 a and a UE 120 r in order to facilitate communication between the BS 110 a and the UE 120 r. A relay station may also be referred to as a relay BS, a relay, etc.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BS, pico BS, femto BS, relays, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network 100. For example, macro BS may have a high transmit power level (e.g., 20 Watts) whereas pico BS, femto BS, and relays may have a lower transmit power level (e.g., 1 Watt).

Wireless communication network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum resource allocation (called a “resource block” (RB)) may be 12 subcarriers (or 180 kHz). Consequently, the nominal Fast Fourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using time division duplex (TDD). Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled, wherein a. A scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

In FIG. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and/or uplink. A finely dashed line with double arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 illustrates example components of BS 110 and UE 120 (as depicted in FIG. 1), which may be used to implement aspects of the present disclosure. For example, antennas 252, processors 266, 258, 264, and/or controller/processor 280 of the UE 120 and/or antennas 234, processors 220, 260, 238, and/or controller/processor 240 of the BS 110 may be used to perform the various techniques and methods described herein.

At the BS 110, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 220 may also generate reference symbols, e.g., for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232 a through 232 t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232 a through 232 t may be transmitted via the antennas 234 a through 234 t, respectively.

At the UE 120, the antennas 252 a through 252 r may receive the downlink signals from the base station 110 and may provide received signals to the demodulators (DEMODs) in transceivers 254 a through 254 r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators 254 a through 254 r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at UE 120, a transmit processor 264 may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source 262 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the demodulators in transceivers 254 a through 254 r (e.g., for SC-FDM, etc.), and transmitted to the base station 110. At the BS 110, the uplink signals from the UE 120 may be received by the antennas 234, processed by the modulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at the base station 110 and the UE 120, respectively. In some embodiments, the controllers/processors 240 and 280 include radar system circuitry 290 and 292 for performing radar detection and radar transmission complementary to vehicle-to-everything (V2X) communication. The processor 240 and/or other processors and modules at the BS 110 may perform or direct the execution of processes for the techniques described herein. The memories 242 and 282 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Example Time Synchronized Radar Transmissions

Radio detection and ranging (radar) is a complementary technology to vehicle-to-everything (V2X) communication that enhances road safety and the driving experience. Radar uses electromagnetic waveforms to detect objects and determine information such as its relative speed and location. Vehicles can use radar to enhance several technologies. For example radar can enable advanced navigation techniques such as accident avoidance and self-driving operations, etc. In accordance with certain aspects of the disclosures, radar detection systems can interface with, or be incorporated into, V2X communication systems.

FIGS. 3A and 3B depict a V2X system in two complementary transmission modes. FIG. 3A shows a first transmission mode using direct communications between participants in the local area. FIG. 3B shows a second transmission mode using network communications through a network, such as an eNodeB.

As illustrated in FIG. 3A, the first transmission mode allows for direct communication between different participants in a given geographic location. For example, a vehicle can communicate with an individual (V2P) (e.g., through a PC5 interface). A vehicle can also communicate and another vehicle (V2V) (e.g., through a PC5 interface). In this case, the PC5 interface relates to a direct connection between vehicles. In some examples, a base station is not required to establish the PC5 interface or to enable communication via the PC5 interface. Highway components, such as a traffic signal or other infrastructure may also be connected to vehicles in (V2I) communication. In each embodiment, each element may be a transmitter and a receiver and capable of two-way communication. In the configuration provided, the first transmission mode is a self-managed system and network assistance is not needed to facilitate the exchange of data. Such transmission modes provide for reduced cost and increased reliability as network service interruptions do not occur during handover operations for moving vehicles. Certain resource assignments for communication may also not need coordination between operators. Additionally, subscription to a network is not necessary.

In certain aspects, a V2X system is configured to work in a 5.9 GHz spectrum, thus any vehicle with an equipped system may access this common frequency and share information (e.g., reference time information (e.g., UTC, a clock signal), codebooks (e.g., radar transmission parameter codebooks), sensor information (e.g., radar transmission parameters), etc.). V2X operations may also use other frequencies for communication (e.g., using 802.11p based communication). In one aspect, the V2X system may be operated in a 10 MHz band that describes/contains basic safety services. In other aspects, the V2X system may be operated over a wider frequency band.

In FIG. 3B, a second of two complementary transmission modes is illustrated. In certain aspects, a vehicle may communicate to another vehicle through network communications. These network communications may occur through discrete nodes, such as an eNodeB, that send and receive information between vehicles and a network. The network communications may be used, for example, for long range communications between vehicles, such as noting the presence of accident miles ahead. Other types of communications may be sent by the node to vehicles, such as traffic flow conditions, road hazard warnings, environmental/weather reports, service station availability, radar detection system information (e.g., reference time information, codebooks, sensor information, etc.), to name a few. Data may also be obtained from cloud-based sharing services. Residential service units (RSUs) may be utilized as well as 4G/5G small cell communication technologies to benefit in more highly covered areas to allow real time information to be shared among V2X users. As the number of RSUs diminishes, the V2X systems may rely more on small cell communications or other technology.

Radar can provide data over a wide range of conditions to improve the driving experience. Radar is able to operate in the day or night and over several miles. Radar can be used to identify multiple objects (e.g., cars, pedestrians, buildings, etc.) at substantially the same time, even in adverse weather conditions. Radar systems transmit electromagnetic waves and receive their reflection off objects. By measuring the time delay between the transmitted and the received waveform, it is possible to determine the distance (or range) that an object is from the transmitter.

For a stationary ranging radar system, distance (D)=½ the time delay between the transmitted and received radar waveform times the speed of the radar waveform (which may be approximated as 3×10⁸ or (C)). Transmitters and receivers can use the same antenna, or groups of antennas, and use circuitry such as a duplexer to control input and output operation. In certain aspects, it is impractical to use single pulse radar systems, as it will be appreciated that for a ten meter target, the time delay is less than 1/10 of a microsecond [(2*10)/(3*10⁸)=66 nanoseconds]. Thus, another approach to radar detection is to use a continuous wave (CW) radar waveform.

Unmodulated CW (UM-CW) radar detection systems transmit a radar waveform at a constant frequency and use any change in frequency in the received radar waveform to determine the speed of an object. UM-CW radar is not typically used to provide range as stationary objects do not generate a frequency change in the received radar waveform. UM-CW radar is commonly used in sports, for example to determine the speed of a baseball or a racecar.

To obtain more information, frequency modulated CW (FM-CW) radar may be used. FIG. 4A depicts three FM-CW radar waveforms (or chirps) on a frequency-time scale. Chirp 402 has a first slope with its frequency originating at (Fc) of zero (or zero offset). Chirp 404 has the same slope as chirp 402 and a positive (Fc) offset. Chirp 406 has a zero offset and a second slope that is lower than the first slope of chirp 402 (lower frequency delta for the same time delta).

FIG. 4B depicts chirp 402 from FIG. 4A on an amplitude-time scale wherein the amplitude (Ac) oscillations increase in frequency over the chirp time. It will be appreciated that in certain aspects, the phase of the chirp may be controlled to provide a desired phase. When an FM-CW chirp is received, it may experience both a change in frequency and a time delay, and therefore can be used to simultaneously measure the relative range (e.g., using the time delay) and the velocity (e.g., using the frequency change) of an object from the radar detection system.

FIG. 5 shows three graphs representative of an object detected by one or more radar waveforms as described below. Radar waveform 502 depicts detecting an object with a single chirp in an environment free from interference. The signal to noise ratio is ideal as the noise is shown as zero. It will be appreciated that environments are rarely free from interference. Radar waveform 504 depicts detecting an object with a single chirp in an environment with interference. It will be appreciated that the signal to noise ratio is poor because the interference is high making object detection poor. Radar waveform 506 depicts the same high interference environment as with radar waveform 504; however, radar waveform 506 is representative of coherent integration (or time-domain averaging) using a number of chirps (e.g., 64 chirps). It will be appreciated that interference is often random, and thus using a plurality of chirps does not increase the signal of the interference because they do not coherently combine. However, it will be appreciated that a received radar signal incident an object will coherently combine, thereby increasing the signal to noise ratio as shown at radar waveform 506. As shown in FIG. 5, the signal to noise ratio of signal 506 is better than signal 504.

FIG. 6 depicts certain aspects of a radar detection system 600 using an FM-CW radar waveform to provide both range and speed using coherent integration. FIG. 6 includes a transmitted FM-CW radar waveform 602, which is a saw-tooth radar waveform with a linear increase in frequency for each chirp, for each chirp time (Tc). In certain aspects, each Tc is about 25 microseconds. Time period Nc represents a time period for a transmission of a plurality of chirps (e.g., 64 chirps), and is also referred to as a frame. It will be appreciated that other FM-CW waveforms, chirp times (Tc), and frame times (Nc) are within the scope of the disclosure.

FIG. 6 further includes a received radar waveform 604. Received radar waveform 604 is shown as shifted to the right of transmitted radar waveform 602 by a time delay. As shown in FIG. 6, though signal processing (e.g., taking the fast Fourier transform (FFT)), it will be appreciated that a range distribution may be determined. It will be further appreciated, that by taking the FFT of the range distributions, a frequency shift (Doppler frequency) may be determined. It will be appreciated that a constant false alarm rate (CFAR) algorithm may be used for further signal processing to aid in detecting an object against interference. The Doppler frequency may be used to determine a relative speed, including zero, that an object is moving. For example, the time delay may indicate that the target is 50 meters away, and the Doppler frequency may indicate that the target is moving at about 1 meter per second away from the radar detection system. As more radar detection systems are deployed, interference is a greater problem.

FIG. 7 illustrates a group of vehicles 700 using a radar detection system according to certain aspects of the disclosure. For example, vehicle 702 is using a radar detection system (e.g., a radar detection system apparatus connected to vehicle 702) and coherent integration to detect objects (e.g., vehicles 704 and 706) using radar waveform 710. When vehicles 704 and 706 are not using radar detection, the reflections from radar waveform 710 coherently combine and the data is used to successfully identify vehicles 704 and 706.

In other aspects, vehicle 704 is also using a radar detection system (e.g., a radar detection system apparatus integrated into vehicle 704) and transmits a radar waveform 720. In FIG. 7, radar waveform 720 is a substantially similar waveform (e.g., slope, offset, and phase) to radar waveform 710. The radar detection system of vehicle 702 may receive radar waveform 720 and determine that radar waveform 720 is a reflected signal of radar waveform 710. In this case, the radar detection system of vehicle 702 determines that there is an object at half the distance to vehicle 704. It will be appreciated that this object is identified in error (or a ghost target). It will be further appreciated that the signal strength of radar waveform 720 as measured at the radar detection system of vehicle 702 is likely to be much stronger than the reflected signal of radar waveform 710 as the strength of a radar signal is inversely proportional to the square of the distance from the source. In certain aspects, because radar waveform 720 is much stronger than the reflected signal of radar waveform 710, vehicle 702 is unable to detect vehicle 706 over the high signal strength of radar waveform 720. Thus there exists a need to eliminate ghost target errors as well as improve the signal to noise ratio in high interference environments.

FIG. 8 shows a series of graphs representative of a radar waveform 800 a and a radar waveform 800 b on a frequency-time scale. Radar waveform 800 a includes a plurality of chirps 802 a to 802 n, with each chirp 802 having a chirp time (Tc) and the plurality of chirps collectively having a frame time (Nc). In certain aspects Tc may be 25 microseconds, and Nc may be frame of 64 chirps, but Tc and Nc may be shorter or longer without deviating from the scope of the disclosure (e.g., a chirp Tc of 10 microseconds, and a frame Nc of 1024 chirps). Each chirp 802 has the same slope, offset, and phase.

Radar waveform 800 b includes a plurality of chirps 804 a to 804 n, each with a different set of radar transmission parameters. Radar transmission parameters can include at least one of a waveform parameter, an antenna parameter, or a modulation parameter.

A waveform parameter includes at least one of a slope, an offset, or a phase. For example, chirp 804 a in FIG. 8 shows a first slope and no offset. Chirp 804 b shows a positive offset and a slope greater than the slope in chirp 804 a. Chirp 804 n has the same slope as chirp 804 a, but a positive offset. The phase of the radar waveform may also be selected as a waveform parameter independently or in connection with any one of chirps 804 a to 804 n. For example, if two vehicles are traveling next to each other down a highway, each vehicle may select (e.g., based in part on a vehicle identification (ID) and a reference time obtained through a V2X communication) a different set of waveform parameters. In certain aspects, a vehicle ID is not used and a different set of waveform parameters are based only on the reference time. In other aspects, a vehicle ID includes multiple vehicle IDs.

An antenna parameter includes at least one of a beam form, a polarization, or an antenna selection. A beam form includes using at least one antenna to direct the propagation path of the radar waveform transmitted and received by a radar detection system. It will be appreciated that in certain aspects, selecting a narrower beam form may reduce interference. For example, if two vehicles are traveling next to each other down a highway, each vehicle may select a narrow forward-facing radar beam form antenna parameter to reduce potential interference from the radar detection system of the nearby vehicle. In other cases, a vehicle may select a wide radar beam form antenna parameter, for example to aid in self-driving operation.

A polarization antenna parameter may also be selected for similar reasons. For example, if a radar detection system of a first vehicle is using a first polarization antenna parameter in a certain area, then a second vehicle may select a second polarization antenna parameter to reduce interference when in the same area.

An antenna selection antenna parameter includes selecting one or more antennas to use for radar detection (e.g., to support beamforming, or for spatial response). It will be appreciated that a radar detection system may have a plurality of antennas, each of which may not have the same spatial response to a radar waveform. Thus, in certain aspects, a radar detection system may select an antenna selection parameter associated with a certain antenna that has a lower interference than another antenna.

A modulation parameter includes at least one of a time division multiplexing (TDM) parameter, or a frequency division multiplexing (FDM) parameter. TDM may be used to define certain on-off patterns for a radar waveform. FDM may be used to define certain frequency subbands for a radar waveform. In certain aspects, a radar detection system may select a modulation parameter based on a reference time and/or a vehicle ID. For example, a radar detection system may select a certain frequency subband based on the subband not being associated with any vehicle ID at a desired transmission time, which may be based on a reference time (e.g., UTC). In certain aspects, a modulation parameter based only on a reference time.

However, as more radar detection systems are deployed, the likelihood of overlapping radar waveforms increases. This is in part because a waveform parameter such as the slope of a chirp may be limited to a certain number of slopes (e.g., because of a hardware limitation). Thus in certain aspects, additional information (e.g., reference time information and/or vehicle ID) is used to improve radar waveform selection in a radar detection system by allowing one or more radar detection systems to synchronize transmissions based on a reference time.

FIG. 9 provides a method 900 for radar detection by an apparatus in accordance with certain aspects of the disclosure. The apparatus may be a stand-alone radar detection system connected to a device (e.g., a vehicle, robot, computing device, etc.) though a wireless connection (e.g., Bluetooth, WiFi, etc.) or physically integrated into the device (e.g., integrated into vehicle electronics during or after manufacturing). In other aspects, the apparatus may be connected, or integrated, into a second device (e.g., a second vehicle) and accessible to the first device (e.g., using V2X communications). It will be appreciated that the apparatus may use its own processor to execute instructions stored on a memory (e.g., local storage, cloud storage, etc.) or it may use a shared processor (e.g., a processor shared with one or more other sensors or device components) to execute instructions. In other aspects the apparatus includes more than one radar detection system working together to perform the operations described in the disclosure.

At block 902, the apparatus selects one or more radar transmission parameters based on a reference time at block 902. The apparatus may be integrated into a vehicle or it may be a stand-alone unit (e.g., connected to a vehicle, in communication with the vehicle (e.g., using V2X communications)).

The reference time (e.g., a universal coordinated time (UTC)) may be acquired in a number of ways. For example, a radar detection system may use a satellite (e.g., a global positioning satellite (GPS) (e.g., the United States global navigation satellite system (GNSS), the Russian GLONASS, the Chinese BeiDou Navigation Satellite System (BDS), or the European Union's Galileo satellite)). In other aspects, the reference time may be acquired from a network (e.g., though eNodeB in FIG. 3B). In other aspects, the reference time may be acquired from V2X communications (e.g., a satellite or network). In other aspects, a reference time may be obtained from a timing device (e.g., a local clock, a remote clock in communication with the radar detection system (e.g., using Bluetooth, WiFi, etc.). It will be further appreciated that a timing device may also be used to locally store (e.g., on memory accessible to the radar detection system) and/or keep time associated with a reference time that may be obtained through a satellite, a network, or another timing device. For example, if a satellite connection is lost, a vehicle may use its local clock to provide a reference time. In certain aspects, a codebook of radar transmission parameters is associated with a reference time (e.g., certain radar transmission parameters are associated with a certain reference time). For example, if a radar detection system wants to perform radar detection at a certain reference time X, it may select certain radar transmission parameters based on the reference time. In other aspects, the if a radar detection system wants to perform radar detection at a certain reference time X for vehicle ID 1, it may select certain radar transmission parameters based on reference time X and vehicle ID 1.

In certain aspects the apparatus selects one or more radar transmission parameters based on a vehicle ID. A vehicle ID may be sent or received over V2X communications (e.g. to other vehicles, a network, or other infrastructure). The vehicle ID may be any digital information used to identify a specific vehicle or group of vehicles. The vehicle ID may further be associated with location information. For example, in certain aspects, a network may determine that two vehicles are located near each other using their vehicle ID and other information, such as their GPS location or location of the closest base station.

Selecting one or more radar transmission parameters based on a reference time and/or a vehicle ID includes selecting radar transmission parameters to reduce interference. For example, if a first vehicle ID is associated with a first set of radar transmission parameters, a second vehicle in the area can use a second set of radar transmission parameters. In certain aspects, the second set of radar transmission parameters are parameters that are determined to have a low interference for the environment (e.g., selecting parameters that are not associated with a vehicle ID in that area). In certain aspects, after a radar detection system of a vehicle selects radar transmission parameters, those radar transmission parameters are associated with the vehicle ID of the vehicle. In certain aspects, a codebook of radar transmission parameters is associated with a vehicle ID (e.g., a vehicle ID is assigned certain radar transmission parameters (e.g., from a network)). At block 904, the apparatus performs the radar detection using the selected radar transmission parameters and the reference time.

FIG. 10 shows radar waveform 1000 that includes chirps 1002 a to 1002 n, with each chirp 1002 having a chirp time (Tc) and the plurality of chirps collectively having a frame time (Nc). Nc may include any number of chirps (e.g., 64 chirps, 128 chirps, 256, chirps, 1024 chirps, etc.). FIG. 10 further shows time window A though time window N. In certain aspects each chirp 1002 is associated with its own time window. For example, Chirp 1002 a is associated with time window A and 1002 b is associated with time window B. In other aspects, a plurality of chirps are associated with a single time window. For example, time window A may be associated with frame Nc including chirp 1002 a to 1002 n. It will be appreciated that each frame may use its own time window, which may or may not be associated with the time window of the previous frame.

In certain aspects, a time window (e.g., time window A) is a fixed time window, and may be specified in microseconds. In other aspects, a time window is a dynamic time window, and may be specified in percent. For example, if the chirp time Tc for chirp 1002 a is 25 microseconds, and time window A is a dynamic time window of 20% of Tc, then time window A is 5 microseconds. It will be appreciated that other parameters may be used to specify the time window (e.g., a fixed time window of 0-10 microseconds, or a percentage of TC between 0-20%).

In certain aspects, performing radar detection using the reference time includes performing the start of a radar detection transmission within time window associated with a chirp boundary and/or a frame boundary (also referred to as synchronizing). In certain aspects, a chirp boundary may be defined by =(Tcurrent/Tchirp)mod(Nchirps), where Tcurrent is a reference time (e.g., UTC) in microseconds, Tchirp is the chirp time in microseconds (e.g., 25 microseconds) and Nchirps is the number of chirps in a transmission (e.g., 1002 a-n in frame Nc). In certain aspects, a frame boundary may be defined by =(Tcurrent/(Tchirps*Nchirps))mod(X), where X is the frame size (e.g., 1024 chirps).

FIG. 10 shows a boundary A which may be a chirp boundary for chirp 1002 a and/or a frame boundary for frame Nc as set forth above. In certain aspects time window A is 5 microseconds, or +/−2.5 microseconds from boundary A. In other aspects, when time window A is 10 microseconds, time window A is +/−5 microseconds from boundary A. As explained above, time window A may also be specified in percent (e.g., up to a fraction (e.g., 10%) of the duration of the chirp time Tc). In other aspects, the time window does not need to be split proportionately around the median.

FIG. 11 illustrates a communications device 1100 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIG. 9. The communications device 1100 includes a processing system 1102 coupled to a transceiver 1108. The transceiver 1108 is configured to transmit and receive signals for the communications device 1100 via an antenna 1110, such as the various signal described herein. The processing system 1102 may be configured to perform processing functions for the communications device 1100, including processing signals received and/or to be transmitted by the communications device 1100.

The processing system 1102 includes a processor 1104 coupled to a computer-readable medium/memory 1112 via a bus 1106. In certain aspects, the computer-readable medium/memory 1112 is configured to store instructions that when executed by processor 1104, cause the processor 1104 to perform the operations illustrated in FIG. 9, or other operations for performing the various techniques discussed herein.

In certain aspects, the processing system 1102 further includes a selecting component 1114 for performing the operations illustrated in block 902 of FIG. 9. Additionally, the processing system 1102 includes a performing component 1116 for performing the operations illustrated in block 904 of FIG. 9. The selecting component 1114 and the performing component 1116 may be coupled to the processor 1104 via bus 1106. In certain aspects, the selecting component 1114 and the performing component 1116 may be hardware circuits. In certain aspects, the selecting component 1114 and the performing component 1116 may be software components that are executed and run on processor 1104.

Additional Considerations

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1), a user interface (e.g., keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer-readable storage medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable storage medium (e.g., tangible media). In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described herein and illustrated in FIG. 9.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims. 

What is claimed is:
 1. A method for radar detection by an apparatus, comprising: selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles; and performing radar detection using the selected radar transmission parameters and the reference time.
 2. The method of claim 1, further comprising selecting one or more radar transmission parameters based on a vehicle identification (ID).
 3. The method of claim 2, wherein the vehicle ID includes digital information configured to identify one or more of a specific vehicle or the group of vehicles.
 4. The method of claim 1, wherein the reference time is based on a universal coordinated time (UTC).
 5. The method of claim 1, wherein the radar transmission parameters comprise at least one of: a waveform parameter, an antenna parameter, or a modulation parameter.
 6. The method of claim 5, wherein the waveform parameter comprises at least one of: a slope, an offset, or a phase.
 7. The method of claim 5, wherein the antenna parameter comprises at least one of: a beam form, a polarization, or an antenna selection.
 8. The method of claim 5, wherein the modulation parameter comprises at least one of: a time division multiplexing (TDM) parameter, or a frequency division multiplexing (FDM) parameter.
 9. The method of claim 1, wherein performing radar detection using the selected radar transmission parameters and the reference time further comprises synchronizing at least one of: a chirp boundary or a frame boundary with the reference time.
 10. The method of claim 9, wherein synchronizing at least one of the chirp boundary or the frame boundary comprises synchronizing a beginning of a chirp transmission or a frame transmission to a time window associated with the reference time.
 11. The method of claim 1, wherein the radar transmission parameters are selected in part based on a codebook.
 12. The method of claim 1, wherein the radar transmission parameters are selected based at least in part on one or more vehicle-to-everything (V2X) communications.
 13. A radar detection apparatus comprising: a memory; and a processor configured to cause the radar detection apparatus to: select one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles; and perform radar detection using the selected radar transmission parameters and the reference time.
 14. The radar detection apparatus of claim 13, wherein the processor is further configured to cause the radar detection apparatus to select one or more radar transmission parameters based on a vehicle identification (ID).
 15. The radar detection apparatus of claim 14, wherein the vehicle ID includes digital information configured to identify one or more of a specific vehicle or the group of vehicles.
 16. The radar detection apparatus of claim 13, wherein the reference time is based on a universal coordinated time (UTC).
 17. The radar detection apparatus of claim 13, wherein the radar transmission parameters comprise at least one of: a waveform parameter, an antenna parameter, or a modulation parameter.
 18. The radar detection apparatus of claim 17, wherein the waveform parameter comprises at least one of: a slope, an offset, or a phase.
 19. The radar detection apparatus of claim 17, wherein the antenna parameter comprises at least one of: a beam form, a polarization, or an antenna selection.
 20. The radar detection apparatus of claim 17, wherein the modulation parameter comprises at least one of: a time division multiplexing (TDM) parameter, or a frequency division multiplexing (FDM) parameter.
 21. The radar detection apparatus of claim 13, wherein performing radar detection using the selected radar transmission parameters and the reference time further comprises synchronizing at least one of: a chirp boundary or a frame boundary with the reference time.
 22. The radar detection apparatus of claim 21, wherein synchronizing at least one of the chirp boundary or the frame boundary comprises synchronizing a beginning of a chirp transmission or a frame transmission to a time window associated with the reference time.
 23. The radar detection apparatus of claim 13, wherein the radar transmission parameters are selected in part based on a codebook.
 24. The radar detection apparatus of claim 13, wherein the radar transmission parameters are selected based at least in part on one or more vehicle-to-everything (V2X) communications.
 25. A means for radar detection by an apparatus, comprising: a means for selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles; and a means for performing radar detection using the selected radar transmission parameters and the reference time.
 26. The apparatus of claim 25, further comprising means for selecting one or more radar transmission parameters based on a vehicle identification (ID).
 27. The apparatus of claim 26, wherein the vehicle ID includes digital information configured to identify one or more of a specific vehicle or the group of vehicles.
 28. The apparatus of claim 25, wherein the means for performing radar detection using the selected radar transmission parameters and the reference time further comprises means for synchronizing at least one of: a chirp boundary or a frame boundary with the reference time.
 29. The apparatus of claim 28, wherein the means for synchronizing at least one of the chirp boundary or the frame boundary comprises a means for synchronizing a beginning of a chirp transmission or a frame transmission to a time window associated with the reference time.
 30. A non-transitory computer-readable storage medium that stores instructions that when executed by a processor of an apparatus cause the apparatus to perform a method of radar detection comprising: selecting one or more radar transmission parameters based on a reference time, wherein the reference time is common to at least a group of vehicles; and performing radar detection using the selected radar transmission parameters and the reference time. 